JPH01235814A - Displacement detecting sensor - Google Patents

Abstract

PURPOSE:To improve reliability by effecting the movement of a light shielding body by the displacement of an object to be detected in a non-contact state by a magnetic material which is separately provided to the side of the object to be detected. CONSTITUTION:The light emitted by a light emitting element is emitted as collimated beams 3a of light by a rod lens 2 via an optical fiber cable 1. The exit light beams 3a are subjected to 90 deg. directional change by a 1st reflecting mirror 6, then to 90 deg. directional change by the 2nd reflecting mirror 6' so that the entire light is projected as the reflected light beams 3b parallel with the exit light beams 3a on the rod lens 2', and is received by the light receiving element via the optical fiber cable 1'. Another magnetic material 16 mounted to the side of the object to be detected is provided to the outside of the magnetic material 15. The magnetic material 15 on the light shielding body 5 side is attracted and moved in a non-contact state as the magnetic material 16 is moved like a dotted line by the displacement of the object to be detected. A light shielding piece 5a is thereby moved and the optical path between the reflecting mirrors 6 and 6' is shut off as shown by the dotted line. The generation of a trouble is thus obviated even if the entire part of the detecting system is hermetically closed and, therefore, the stable state is maintained over a long period of time and the reliability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a displacement detection sensor that optically detects the presence or absence of displacement when a detected object is displaced.

[Prior art and problems] For example, in order to monitor the stroke movement of a cutting tool in a precision machine tool, a light emitting/receiving element is placed at a predetermined position. A light-shielding plate that is displaced by movement is provided, and the light emitting and
There is a displacement detection sensor that detects whether the cutting tool is operating with an accurate stroke by moving the light shielding plate in and out of the optical system path of the light receiving element. This type of displacement detection sensor differs from conventional electric contact type sensors in that the detection means is non-contact type, so there is no problem of wear and tear on the contact parts, and the service life can be greatly extended. It has many advantages, such as fewer malfunctions and can contribute to improved reliability, and has recently attracted attention as optical-related systems continue to advance.

4 and 5 show two conventional optical displacement sensors of this kind.
An example is shown below.

FIG. 4 shows an example of using a prism 4 for reflecting light, in which light emitted from a light emitting element (not shown) is guided through an optical fiber 1a, and the emitted light is made into parallel light by a rod lens 2. 3a is reflected by the prism 4 to produce reflected light 3b.
In the optical path portion of the reflected light 3b, which is configured to be inputted from the rod lens 2'' and received by a light receiving element (not shown) via the optical fiber 1a,
A light-shielding plate 5 is provided that displaces in the direction of the arrow in the figure in accordance with the displacement of a detected object (not shown), and when the light-shielding plate 5 displaces and moves to the dotted line position, it blocks the optical path of the reflected light 3b. ,
By being displaced again and returning to the solid line position, the optical path of the reflected light 3b is opened. In this way, the light receiving element detects the presence or absence of the reflected light 3b, thereby detecting the displacement of the object to be detected.

In Fig. 5, two reflecting mirrors 16.6- with 45° reflecting surfaces are installed in place of the prism 4 in Fig. 4, and in the case of this embodiment, two reflecting mirrors are used. A light shielding plate 5 is placed between 6 and 6 to block the optical path between the reflecting mirrors.Depending on the installation conditions of the sensor, it may be more efficient to install the light shielding plate 5 at such a position. Selected in case.

However, the conventional sensor shown in FIGS. 4 and 5 has the following problems.

The first problem is that the displacement movement of the light shielding plate 5 is performed by mechanical contact with the object to be detected.

It is true that the displacement detection means is carried out in an optical non-contact state, but if the light shielding plate is moved by the contact method, it is ultimately not much different from the conventional electrical contact method, and wear of the contact part is inevitable. However, it is still difficult to avoid the risk of malfunction.

Second, in many cases it is desirable to store the sensor part inside a case to protect it from dust, humidity, external force, radiation, etc. However, as mentioned above, since the light shielding plate is displaced by mechanical contact, The problem is that it cannot be completely sealed. In order to dare to carry out this, the object to be detected must also be placed inside the case.
It is unavoidable that the size will become extremely large.

[Object of the Invention] The present invention eliminates the drawbacks of the prior art as described above, and not only makes it possible to completely seal the sensor part in an optical displacement detection sensor, but also makes it possible to completely seal the sensor part in an optical displacement detection sensor. The present invention also aims to provide a novel optical displacement detection sensor that can be completely non-contact type.

[Summary of the invention] The present invention utilizes magnetic force to displace a light shielding body,
At least a part of the light shielding body is made of a magnetic material, and the optical system for detecting displacement and the light shielding body are housed in a sealed case, while the movement of the light shielding body is caused by the magnetic body outside the sealed case toward the magnetic body on the light shielding body side. The light shielding body is constructed so that it can be displaced by inducing the movement of the light shielding body, thereby making it possible to displace the light shielding body in a completely non-contact manner, and also making it possible to store the entire body in a sealed case. .

[Example] The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a specific example of the configuration of a displacement detection sensor according to the present invention.

1.1'' is an optical fiber cable having an optical fiber inside; 7.7- is a connector attached to the end of the optical fiber cable; 8.8- is a receptacle paired with the connector 7.7''; 2. 2' is the receptacle 8, 8-
This is a rod lens installed at the end of the optical fiber.

Light emitted by a light emitting element (not shown) is emitted from the rod lens 2 via the optical fiber of the optical fiber cable 1 as parallel emitted light 3a.

At the front of the emitted light 3a, there is a first mirror having a reflective surface in the 45° direction.
There is a reflection jfi6, and the light whose direction is changed by 90 degrees by the reflector 6 is reflected once again by 90 degrees by the second reflector 6゛.
The direction is changed to 0°, and the reflected light 3b becomes parallel to the emitted light 3a, and all the light enters the rod lens 2'' and is received by a light receiving element (not shown) via the optical fiber cable 1''.

On the other hand, in this embodiment, the emitted and reflected lights 3a and 3b
There is a light shielding body 5 that can move back and forth in a direction parallel to the light shielding body 5.
A part of the light shielding piece 5a is formed on a light shielding piece 5a, and by moving the light shielding piece 5a to a position indicated by a dotted line in the figure, the optical path can be blocked between the reflecting mirrors 6 and 6-. Reference numeral 11 denotes a holder that holds the light shield 5, and 12 is a square piece that is attached to the tip of the light shield 5 and can move within the space 11a of the holder 11 in the moving direction of the light shield 5.

FIG. 2 is a partial cross-sectional view of the holder 11 constructed as described above, and FIG. 3 is a cross-sectional view taken along the line AA in FIG. The square piece 12 is formed into a square shape (not limited to four corners) as shown in the figure and is fixed to the main body 5b of the light shielding body 5, and the space 11a of the holder 11 also has a cross section 4 corresponding to the outer shape of the square piece 12. By being formed into a rectangular shape, the light shielding body 5 can move forward and backward without rotating. 13
14 is a spring for returning the light shielding body 5 that moves forward and backward as described above to the home position; 14 is the light shielding body 5;
15 is a magnetic body attached to the outer shell of the light shielding body "5.Magnetic body 15
There is a separate magnetic body 16 attached to the side of the object to be detected (not shown) on the outside of the body, and when the outer magnetic body 16 moves as shown by the dotted line in FIG. The magnetic body 15 is attracted and moved in a non-contact manner, thereby moving the light shielding piece 5a, and the reflection m6.6-
The structure is such that the optical path between them is blocked as shown by the dotted line in FIG.

Although there is no difference in function even if the optical system path, reflector, light shielding body, etc. configured as above are placed in an exposed position, they must be protected from dust, external force, moisture, etc. when applied to precision equipment. To protect the whole, Patsukin 9.9-
It is desirable and possible to house the device in a sealed case 10 having a

That is, in the present invention, since it is possible to displace the light shielding body in a non-contact manner as described above, no problem occurs even if the entire detection system is sealed. 1st
As shown in the figure, the entire device is housed in a sealed case 10, and a magnetic body 16 on the side of the detected object is placed outside the case 10. Since the light shielding body 5 is displaced by mutual attraction due to the magnetic force of the outer magnetic body 16 and the light shielding side magnetic body 15, there is no operational problem even if the outer wall of the case exists between the magnetic bodies 15 and 16. This makes it possible to house the detection system in a sealed case, which has been impossible in the past, and makes it possible to ensure more precise operation and associated reliability.

Note that when stored in the sealed case 10, the external magnetic body 1
The magnetic body 15 of the light shielding body 5 operated by the external magnetic body 1 is arranged as close to the inner wall of the case 10 as possible.
For this purpose, as shown in FIG. 1, the outer shell of the light shielding body 5 should be extended toward the inner wall of the case 10, and the magnetic body 15 should be attached to its tip. It is preferable to install windows 5c and 5''C in the extended portion of the light shielding body 5, so that the extended portion becomes the optical path 3a.

What is necessary is to avoid it becoming an obstacle to 3b.

The material of the sealed case 10 needs to be non-magnetic, and suitable plastic materials or metals such as steel or aluminum are suitable. Also,
The detection distance can be adjusted by adjusting the length of the light shielding piece 5a.4 [Effects of the Invention] As described above, the displacement detection sensor according to the present invention can exhibit the following excellent effects. can.

(1) Since the displacement movement of the object to be detected can be detected without any contact, there are no damaged parts due to wear etc.
There are no failures like those seen with contact type systems, and the system maintains a stable state over a long period of time, greatly contributing to improved reliability.

(2) Since it is a non-contact type, the entire detection system can be housed in a sealed case, making it possible to maintain accuracy through dustproofing and moistureproofing.

(3) By storing it in a case and using an all-optical system, external noise can be sufficiently eliminated, which has a significant effect on improving reliability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an embodiment according to the present invention, and FIG.
The figure is a partial cross-sectional view of the vicinity of the holder, and Figure 3 is A in Figure 2.
-A cross-sectional view, FIGS. 4 and 5 are explanatory diagrams showing two embodiments of the conventional configuration. 1.1-: Optical fiber cable, 2.2-: Rod lens, 3a two-output light, 3b = reflected light, 5: Light shielding body, 5a: Light shielding piece, 6.6-: Reflector, 7.7-: Connector , 8.8°: Receptacle, 10: Sealed case, 11: Holder, 12: Square piece, 13 Spring, 14: Bearing, 15.16: Magnetic material. Agent Patent Attorney Fujio Sato Figure 1 g, e': Shi17'Taku IIO: Asahikawa Booth A-A Total 1 Figure 1JE4

Claims (2)

[Claims] (1) A light shielding body that is movable according to the displacement of the object to be detected is arranged in the middle of the optical system path where the light emitted from the light emitting element is received by the light receiving element, and at least a part of the light shielding body is attached with a magnetic material. A displacement detection sensor configured such that a light shielding body can be moved in a non-contact manner by a magnetic body separately provided on the side of the detected object due to displacement of the detected object. (2) Two reflecting mirrors that reflect the emitted light from the light emitting/receiving end and the light emitting end in a direction parallel to the emitted light are housed in the sealed case, and the light shielding body which is also housed in the sealed case is At least a part thereof is made of a magnetic material and is configured to be movable back and forth in a direction parallel to the emitted and reflected light, and the light blocking piece of the light blocking body is configured to be able to block light between the two reflective mirrors. The displacement detection sensor is configured such that when there is a displacement of the object to be detected, the magnetic body outside the sealed case can induce displacement movement in the magnetic body of the light shielding body inside the case in a non-contact manner.